Lightroom SDK: Bug in photo:getRawMetadata ("durationInSeconds")?

In LR 3, the field "durationInSeconds" returned by photo:getRawMetadata() is a number. But in LR 4, it's a userdata that tostring() shows as "RatioTime( 1847/6 )". Some tedious experimentation (absent documentation) shows that the method toNumber() will convert it to a number.

Was it intentional to return this field as a built-in object? I suspect that this is a bug, that the intention was to convert the RatioTime to a number before returning it to the client caller. All other SDK objects have names that start with "Lr".